Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['h', 's', 'c', '1785', '5027', 'v', '5591', 'g', 'a', 'w']

a, c, g, h, s, v, w